1. Field of the Invention
The invention relates to the field of the fabrication of integrated circuit dies and in particular to dies which have been tested and determined to be good.
2. Description of the Prior Art
In some applications the starting product is an integrated circuit die, i.e. a semiconductor chip with finished devices in the chip, but without leads or any packaging. The manufacture of dense electronic packaging is one such application. See U.S. Pat. Nos. 5,953,588 and 6,072,234, incorporated herein by reference, in which multichip modules MCMs are described. Because of the high demand for dies and the high capital investment necessary to be a mass manufacturer of them, it is difficult economically to induce a mass fabricator of dies to manufacture only dies as opposed to the usual finished product, which is a packaged or encapsulated integrated circuit. Such mass fabricators are typically fully occupied with the manufacture of finished integrated circuits. Chips are not typically offered for sale either in wafer or in die form.
Even in those cases where a mass fabricators can be induces to manufacture and sell a bare functional die, the dies are delivered in wafers or diced without testing. In other words, normally a die is tested after it is connected to its lead frame and packaged to ascertain whether it is operable as intended. Mass testing of bare dies is not a procedure that many or any mass fabricators are equipped to do. Therefore, a purchaser of bare dies must test each die individually himself in order to determine its operability or the yield. Bare die testing is too limited to ensure acceptable yields, while comprehensive testing and burn-in renders bare die production cost ineffective. These problems are known as the Know Good Die or KGD problem.
What is needed is some type of method whereby known good bare dies can be economically and practically obtained.